look at it like this, you want to modify what you type based on certain conditions, for example replacing lol in what you type with *Laff*Out*Loud* but if you are quoting (pasting) some text that has lol in it you do not want to change it.
when I type {
if (I have the CTRL key held down) { just show what I typed with no changes, then stop }
change lol to *laff*out*loud*
stop
}
on *:input:#:{
if ($ctrlenter == $true) { return }
say $replace($$1-,lol,*Laff*Out*Loud*)
halt
}
using Return stops the rest of the script from running and and so mIRC posts the text unmodified.
The Halt is needed to stop mIRC from posting the text unmodified as well as the modified version.